* tree.c (tree_expr_nonnegative_p): New function.

        * tree.h (tree_expr_nonnegative_p): Declare.

        * c-typeck.c (build_binary_op): Call `tree_expr_nonnegative_p' to
        elide some sign_compare warnings.
        (build_conditional_expr): Likewise.

cp:
        * typeck.c (build_binary_op): Call `tree_expr_nonnegative_p' to elide
        some sign_compare warnings.

From-SVN: r33019